Fungicidal compositions containing N-acetonylbenzamides

ABSTRACT

The present invention relates to fungicidal compositions and their use as a method for controlling phytopathogenic fungi comprising the application of a selected fungicidally active N-acetonylbenzamide compound and a second fungicidally active compound which is [2-methyl-1-[1-(4-methylphenyl)-ethylaminocarbonyl]-propyl]-carbamic acid, isopropyl ester to plant seed, to plant foliage or to a plant growth medium. The compositions and method of use provide higher fungicidal activity than separate use of the same compounds.

The present invention relates to new fungicidal compositions and their use as a method for controlling phytopathogenic fungi on plants.

It is always desirable to improve products which can be used by growers in order to combat fungal diseases of crops, and in particular diseases caused by fungi in the class Oomycetes.

It is also always desirable to reduce the doses of chemical products spread into the environment to combat fungal attacks on crops, in particular by reducing the application doses of the products.

It is also always desirable to increase the number of antifungal products available to growers in order that they will find, among these products, the one which is best suited to the grower's specific use.

One objective of the invention is thus to provide novel fungicidal compositions which are useful against the problems outlined above.

Another objective of the invention is to propose novel fungicidal compositions which are useful in the preventive and curative treatment of diseases caused by fungi of the class Oomycetes.

Still another objective of the invention is to propose novel fungicidal compositions which are of improved efficacy against mildew and/or late blight caused by Oomycetes.

Yet another objective of the invention is to propose novel fungicidal compositions which are of improved efficacy against downy mildew in grapes and other crops and/or late blight in tomatoes and potatoes.

It has now been found that these objectives may be achieved, partly or totally, by means of the fungicidal compositions according to the present invention.

U.S. Pat. Nos. 5,304,572 and 5,677,333 disclose applying mixtures of the N-acetonylbenzamides disclosed therein with other fungicidal compounds. It has now been discovered that application of the N-acetonylbenzamides disclosed in these patents in combination with selected other fungicidal compounds provides unexpectedly high fungicidal activity and is effective in controlling phytopathogenic fungi at lower N-acetonylbenzamide dosage rates than those disclosed in the U.S. Pat. No. 5,304,572 patent. Although U.S. Pat. No. 5,677,333 discloses the use of N-acetonylbenzamides in combination with ethylene bisdithiocarbamates, cymoxanil and dimethomorph to provide unexpectedly high fungicidal activity, the synergistic combinations of this invention are not disclosed or suggested in that patent.

In a first embodiment of this invention, there is provided a composition comprising

(a) a fungicidally effective amount of a first fungicidally active compound having the formula (I) ##STR1## or an agronomically acceptable salt thereof wherein

R¹ and R³ are each independently halo or (C₁ -C₄)alkyl,

R² is (C₁ -C₄)alkyl, (C₂ -C₄)alkenyl, (C₂ -C₆)alkynyl, (C₁ -C₄)alkoxy or cyano,

R⁴ and R⁵ are each independently a hydrogen atom or (C₁ -C₄)alkyl, provided that at least one of R⁴ and R⁵ is (C₂ -C₄)alkyl and

X is halo, thiocyano or isothiocyano;

(b) a fungicidally effective amount of a second fungicidally active compound which is [2-methyl-1-[1-(4-methylphenyl)-ethylaminocarbonyl]-propyl]-carbamic acid, isopropyl ester; and

(c) an agronomically acceptable carrier.

In a second embodiment of this invention, there is provided method for controlling phytopathogenic fungi on a plant comprising the application of

(a) a fungicidally effective amount of a first fungicidally active compound having the formula (I) ##STR2## or an agronomically acceptable salt thereof wherein

R¹ and R³ are each independently halo or (C₁ -C₄)alkyl,

R² is (C₁ -C₄)alkyl, (C₂ -C₄)alkenyl, (C₂ -C₆)alkynyl, (C₁ -C₄)alkoxy or cyano,

R⁴ and R⁵ are each independently a hydrogen atom or (C₁ -C₄)alkyl, provided that at least one of R⁴ and R⁵ is (C₂ -C₄)alkyl and

X is halo, thiocyano or isothiocyano;

(b) a fungicidally effective amount of a second fungicidally active compound which is [2-methyl-1-[1-(4-methylphenyl)-ethylaminocarbonyl]-propyl]-carbamic acid, isopropyl ester; and

(c) an agronomically acceptable carrier

to the plant seed, to the plant foliage or to the growth medium for the plant.

When R⁴ and R⁵ are different, optical enantiomers of the compounds of the present invention are possible due to the presence of an asymmetric carbon atom linking R⁴ and R⁵. It is known that many biologically active compounds have optical enantiomers, one of which is more active than the other. Similarly, for compounds used in the method of the present invention, the biological activity of one enantiomer may exceed that of the other enantiomer, as described in EP 0 816 330 A1, Jan. 7, 1998.

"(C₁ -C₄)alkyl" means a straight or branched alkyl group having one to four carbon atoms per group and includes methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl.

"(C₂ -C₄)alkenyl" means a straight or branched alkenyl group having two to four carbon atoms per group and includes, for example, ethenyl, 2-propenyl, 2-butenyl, 1-methylethenyl, 2-methyl-2-propenyl and the like.

"(C₂ -C₆)alkynyl" means a straight or branched alkynyl group having from two to six carbons per group and includes, for example, ethynyl, 2-propynyl, 2-butynyl and the like.

"Halo" means chloro, fluoro, bromo and iodo.

"(C₁ -C₄)alkoxy" means a straight or branched alkoxy group having one to four carbon atoms per group and includes, for example, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy and tert-butoxy.

"Cyano" means a group having the structural formula --CN.

"Thiocyano" means a group having the structural formula --SCN.

"Isothiocyano" means a group having the structural formula --NCS.

Agronomically acceptable salts include, for example, metal salts such as sodium, potassium, calcium and magnesium salts, ammonium salts such as isopropyl ammonium salts and trialkylsulfonium salts such as triethylsulfonium salts.

[2-methyl-1-[1-(4-methylphenyl)-ethylaminocarbonyl]-propyl]-carbamic acid, isopropyl ester is a compound represented by formula (II): ##STR3##

The first fungicidally active compound may be a single compound of formula (I) or, alternatively, may be a mixture of compounds of formula (I). Suitable compounds of formula (I) include, but are not limited to,

N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide,

N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-ethylbenzamide,

N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-ethoxybenzamide,

N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methoxybenzamide,

N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-cyanobenzamide, and

N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dibromo-4-methylbenzamide.

In a preferred embodiment, the first fungicidally active compound is

N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide,

N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dibromo-4-cyanobenzamide or a mixture thereof

More preferably, the N-acetonyl benzamide compound is N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide.

The method of the present invention may optionally further comprise application of other compounds having biological activity, for example, additional fungicidally active compounds or compounds having herbicidal activity or insecticidal activity, to the plant seed, to the plant foliage or to the growth medium for the plant.

The method of the present invention is useful for the control of phytopathogenic fungi on crops and the first and second fungicidally active compounds may be applied as a soil fungicide, as a seed protectant, as a foliar fungicide or as a combination thereof. In a preferred embodiment, the first and second fungicidally active compounds are applied to a plant growth medium, to the plant seed or to plant foliage at dosage rates of from 2 parts by weight (pbw) to 90 pbw, more preferably from 5 pbw to 75 pbw, of the first fungicidally active compound per 100 pbw of the combined amount of first and second fungicidally active compounds and from 10 pbw to 98 pbw, more preferably from 25 pbw to 95 pbw, of the second fungicidally active compound per 100 pbw of the combined amount of first and second fungicidally active compounds.

As a soil fungicide, the first and second fungicidally active compositions can be incorporated in the soil or applied to the surface of the soil at a dosage rate of about 0.25 kg to 5 kg of the first fungicidally active compound and from 0.25 kg to 5 kg of the second fungicidally active compound per hectare.

As a seed protectant, the first and second fungicidally active compounds are coated on seed at a dosage rate of about 0.5 kilograms (kg) to 5 kg of the first fungicidally active compound and from 0.5 kg to 5 kg of the second fungicidally active compound per 100 kg seed.

As a foliar fungicide, the first and second fungicidally active compounds are applied to plant foliage at a dosage rate of from 0.01 kg per hectare to 5 kg per hectare of the first fungicidally active compound, and a dosage rate of from 0.01 kg per hectare to about 5 kg per hectare of the second fungicidally active compound. In a preferred embodiment, the first fungicidally active compound is applied to plant foliage at a dosage rate of from 0.05 kg per hectare to about 0.5 kg per hectare. In a preferred embodiment, the second fungicidally active compound is applied to plant foliage at a dosage rate of 0.05 kg per hectare to 2.0 kg per hectare. The first and second fungicidally active compounds can be applied to plant foliage as fungicidal sprays by methods commonly employed, such as conventional high-gallonage hydraulic sprays, low-gallonage sprays, air-blast, aerial sprays and dusts. While the dilution and rate of application will depend upon the type of equipment employed, the method and frequency of application desired and diseases to be controlled, the effective amount is typically from about 0.1 kg to about 5 kg, preferably 0.2 kg to 2.5 kg, of both the first and second active compounds per hectare.

The first and second fungicidally active compounds may be applied simultaneously or sequentially.

In a preferred embodiment, the first and second fungicidally active compounds are simultaneously applied to plant growth medium, the plant seed, plant foliage or a combination thereof as a composition comprising a mixture of the first fungicidally active compound and second fungicidally active compound. In the preferred embodiments, the mixture includes from 2 pbw to 90 pbw of a first fungicidally active compound and from 10 pbw to 98 pbw of a second fungicidally active compound per 100 pbw of the mixture.

In an alternative embodiment, the first and second fungicidally active compounds are applied sequentially to the plant seed, plant foliage or plant growth medium, with application of the second-applied compound following application of the first-applied compound by up to 72 hours. The compounds may be applied in either order: either the first fungicidally active compound followed by the second fungicidally active compound or, alternatively, as application of the second fungicidally active compound followed by the first fungicidally active compound.

The method of the present invention is useful in controlling certain phytopathogenic fungi, particularly fungi of the class Oomycetes, and provides high fungicidal activity and relatively low phytotoxicity. The method of the present invention is particularly effective in controlling Oomycete fungi of the genera Phytophthora, Plasmopara, Peronospora, Albugo and Pseudoperonospora, and even more particularly against the organisms of those genera that cause diseases such as late blight in tomatoes and potatoes and downy mildew in grapes and other crops, including, for example, Phytophthora infestans, Plasmopara viticola and Pseudoperonospora cubensis.

For each of the above disclosed purposes, the first and second fungicidally active compounds can be used in the technical or pure form as prepared, as solutions or as formulations. The compounds are usually taken up in a carrier or are formulated so as to render them suitable for subsequent use as fungicides. For example, the compounds can be formulated as wettable powders, dry powders, emulsifiable concentrates, dusts, granular formulations, aerosols, or flowable emulsion concentrates. In such formulations, the compounds are extended with a liquid or solid carrier and, when dried, suitable surfactants are incorporated. It is usually desirable, particularly in the case of foliar spray formulations, to include adjuvants, such as wetting agents, spreading agents, dispersing agents, stickers, adhesives and the like in accordance with agricultural practices. Such adjuvants commonly used in the art can be found in McCutcheon's "Emulsifiers and Detergents", McCutcheon's "Emulsifiers, and Detergents/Functional Materials" and McCutcheon's "Functional Materials" all published annually by McCutcheon Division of MC Publishing Company (New Jersey).

In general, the compositions utilized in this invention can be dissolved in appropriate solvents such as acetone, methanol, ethanol, dimethylformamide or dimethyl sulfoxide and such solutions extended with water. The concentrations of the combined first and second active compounds in the solution can vary from 1% to 90% with a preferred range being 5% to 50%.

For the preparation of emulsifiable concentrates, the compositions used in the invention can be dissolved in suitable organic solvents or a mixtures of solvents, together with an emulsifying agent which permits dispersion of the first and second active compounds in water. The concentration of the combined first and second active compounds in emulsifiable concentrates is usually 10% to 90% and in flowable emulsion concentrates, this can be as high as 75%. Wettable powders suitable for spraying, can be prepared by admixing the composition with a finely divided solid, such as clays, inorganic silicates and carbonates, and silicas and incorporating wetting agents, sticking agents, and/or dispersing agents in such mixtures. The concentration of the combined first and second active compounds in such formulations is usually in the range of 20% to 98%, preferably 40% to 75%.

Dusts are prepared by mixing the composition of the present invention, or salts and complexes thereof, with finely divided inert solids which can be organic or inorganic in nature. Inert materials useful for this purpose includes botanical flours, silicas, silicates, carbonates and clays. One convenient method of preparing a dust is to dilute a wettable powder with a finely divided carrier. Dust concentrations containing 20% to 80% of the combined first and second active compounds are commonly made and are subsequently diluted to 1% to 10% use concentration.

The method of the present invention, wherein an N-acetonylbenzamide and a selected second fungicidally active compound are applied to plant seed, plant foliage or to a plant growth medium, unexpectedly provides higher fungicidal activity than the same compounds used separately.

The results provided by the mixtures were compared with the predicted results that were calculated using the formula set forth by S. R. Colby in Weeds 1967, 15, 20-22 ("Colby's Formula") from the results obtained using each of the compounds individually. The predicted results are also provided in the following Example. This example, table and experimental procedure are provided for guidance to the practitioner and are not meant to limit the scope of the invention which is defined by the claims.

EXAMPLE 1 Test to Control Phytophthora infestans Using N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide (Compound A) and [2-methyl-1-[1-(4-methylphenyl)-ethylaminocarbonyl]-propyl]-carbamic Acid, Isopropyl Ester (Compound Z)

Bintje variety potatoes were planted at the Campinas, Brasil Research Farm during the 1995 season. Irrigation and natural infection were used to develop the disease. Fungicidal applications were made with standard hydraulic spraying equipment equipped to deliver 640 l/ha of fungicidal spray solution. Eight applications were made on a seven day spray interval schedule. The data used in the calculations was recorded 2 days after the eight spray.

Synergism was observed at a 1:1 ratio of N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide to Compound Z for potato late blight (PLB) disease. The results are reported in Table 1.

                  TABLE 1                                                          ______________________________________                                         Potato Late Blight                                                                                             % Control                                                                             % Control                                 Treatment Kg ai/ha % Infection Observed Expected                             ______________________________________                                         Cmpd. Z 0.180      77.5       18                                                  0.300 63.8 32.5                                                               Cmpd. A 0.100 78.8 16.6                                                         0.150 71.3 24.6                                                                0.200 48.8 48.6                                                               Cmpd. A +  0.100 + 0.100 76.3 19.2                                             Cmpd. Z 0.150 + 0.150 60.0 36.5 31.5.sup.(1)                                 ______________________________________                                          .sup.(1) The value for % control obtained with 0.18 kg/ha of compound Z        alone (18%) was used to determine the % control calculated using the Colb      formula, although the actual concentration of compound Z in the mixture        was lower (0.15 kg/ha). Therefore it can be assumed that the % control         calculated may have been overestimated and the synergistic response could      be greater.                                                              

EXAMPLE 2 Test to Control Plasmopara viticola Using N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide (Compound A) and [2-methyl-1-[1-(4-methylphenyl)-ethylaminocarbonyl]-propyl]-carbamic Acid, Isopropyl Ester (Compound Z)

A 5-7 year old planting of Delaware grapes on a single trellis located at the Newtown, Pa. farm were utilized in the evaluation of grape downy mildew (GDM). Disease was encouraged by the inoculation of border rows with the fungus. Sprinkler irrigation was used to increase the humidity and increase disease development.

Single vine plots separated by untreated vines were used. Four replications in a randomized block were sprayed with the various fungicidal compounds. A 14 day interval was used with one interval stretched to 21 days due to slow disease development.

Applications were made with awand type sprayer using water as the carrier. The water volume used was 1000 l/ha. Disease progress was recorded as percent infection and percent defoliation. For the purposes of this document the calculations were based on the amount of defoliation present 48 days after the last application.

Synergism was observed at a ratio of 2:1 of N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide to Compound Z for grape downy mildew disease. The results are reported in Table 2.

                  TABLE 2                                                          ______________________________________                                         Grape Downy Mildew                                                                                             % Control                                                                             % Control                                 Treatment Kg ai/ha % Infection Observed Expected                             ______________________________________                                         Cmpd. Z 0.225      22.5       0                                                  Cmpd. A 0.100 5.5 68.8                                                          0.200 7.8 55.4                                                                Cmpd. A +  0.200 + 0.100 3.8 78.7 54.9.sup.(1)                                 Cmpd. Z                                                                      ______________________________________                                          .sup.(1) The value for % control obtained with 0.225 kg/ha of compound Z       alone (0%) was used to determine the % control calculated using the Colby      formula, although the actual concentration of compound Z in the mixture        was lower (0.1 kg/ha). Therefore it can be assumed that the % control          calculated may have been overestimated and the synergistic response could      be greater.                                                              

EXAMPLE 3 Test to Control Phytophthora infestans and Plasmopara viticola Using N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide (Compound A) and [2-methyl-1-[1-(4-methylphenyl)-ethylaminocarbonyl]-propyl]-carbamic Acid, Isopropyl Ester (Compound Z)

Three week old tomatoes, var. Pixie, and 4-5 week old potatoes from seed, var. Homestead F1 hybrid, were inoculated with the late blight fungus, Phytophthora infestans, 24 hours following application of the fungicides. Disease evaluations were collected as percent infection and transformed to percent control for the purposes of the calculations.

Grapes, var. Delaware, from tissue culture were 2-3 weeks old when the chemicals were applied. Downy mildew, Plasmopara viticola, inoculations were completed 24 hours after application.

All of the plants were kept in a humidity cabinet for 24 hours to allow infection to occur and then placed in controlled temperature chambers for the duration of the test. Disease evaluations were made 5-6 days after inoculation.

The following Tables 3a, 3b and 3c show that synergism can be detected at ratios ranging from 1:15 to 5:1 of N-[3'-(1'-chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide to Compound Z. The combination of these products provides a wide range of combinations which are synergistic in nature.

                  TABLE 3a                                                         ______________________________________                                         Tomato Late Blight                                                                                                  % Control                                   Treatment g ai/ha % Control Observed Calculated                              ______________________________________                                         Cmpd. A      5       15.8                                                         19 47.4                                                                        75 71.1                                                                       Cmpd. Z  5 42.1                                                                 19 71.1                                                                        75 99.7                                                                       Cmpd. A + Cmpd. Z  5 + 19 79.0 75.6                                              5 + 75 100 99.8                                                              Cmpd. A + Cmpd. Z 19 + 5  71.1 69.5                                             19 + 19 86.0 84.8                                                              19 + 75 99.5 99.8                                                           ______________________________________                                    

                  TABLE 3b                                                         ______________________________________                                         Potato Late Blight                                                                                                  % Control                                   Treatment g ai/ha % Control Observed Calculated                              ______________________________________                                         Cmpd. A      5       72.5                                                         19 73.7                                                                        75 93.7                                                                       Cmpd. Z  5 15                                                                   19 61.2                                                                        75 98.5                                                                       Cmpd. A + Cmpd. Z  5 + 19 96.2 89.3                                              5 + 75 98.7 98.7                                                             Cmpd. A + Cmpd. Z 19 + 5  80.0 77.6                                             19 + 19 96.2 89.8                                                              19 + 75 100 99.6                                                            ______________________________________                                    

                  TABLE 3c                                                         ______________________________________                                         Grape Downy Mildew                                                                                                  % Control                                   Treatment g ai/ha % Control Observed Calculated                              ______________________________________                                         Cmpd. A      5       18.3                                                         19 23.7                                                                        75 38.7                                                                       Cmpd. Z  5 23.7                                                                 19 55.0                                                                        75 80.0                                                                       Cmpd. A + Cmpd. Z  5 + 75 88.7 83.7                                            Cmpd. A + Cmpd. Z 19 + 5  48.7 41.8                                             19 + 19 77.5 65.7                                                              75 + 19 85.0 72.4                                                           ______________________________________                                     

We claim:
 1. A fungicidal composition comprising synergistic fungicidally effective amounts of(a) a first fungicidally active compound which is N-[3'-(1'-(chloro-3'-methyl-2'-oxopentan)]-3,5-dichloro-4-methylbenzamide, (b) a second fungicidally active compound compound which is [2-methyl-1-[1-(4-methylphenyl)-ethylaminocarbonyl]-propyl]-carbamic acid, isopropyl ester, and (c) an agronomically acceptable carrier.
 2. A method for controlling phytopathogenic fungi on a plant comprising the application of a synergistic fungicidally effective amount of the composition of claim
 1. 3. The method of claim 2 wherein the phytopathogenic fungi belong to the class Oomycetes and are of the genera Phytophthora, Plasmopara, Peronospora, Albugo or Pseudoperonospora.
 4. The method of claim 2 wherein the plant is a potato plant, a tomato plant or a grape plant.
 5. The method of claim 2 wherein the amounts of the first and second fungicidally active compounds applied comprise from 2 parts by weight to 90 parts by weight of the first fungicidally active compound and from 10 parts by weight to 98 parts by weight of the second fungicidally active compound per 100 parts by weight of the combined amount of the first and second fungicidally active compounds. 